1. Field of the Invention
The present invention relates to an actuator using an electromechanical transducer and a drive pulse generating apparatus suitable for driving the actuator.
2. Prior Art
Various actuators have conventionally been used for driving a member constituting a precision apparatus of a camera, an XY stage or the like and as an actuator which is small-sized, light-weighted and capable of carrying out fine positioning, there has been proposed by the applicant an electromechanical transducer, for example, a linear progressing type actuator which is constituted to generate elongation and contraction displacement in a piezoelectric element, transmit the elongation and contraction displacement to a drive member and move a driven member via a moving member frictionally coupled to the drive member (U.S. Pat. No. 5,589,723).
Although drive pulses of sawtooth waves are used in a linear progressing type actuator or a rotary type actuator using an electromechanical transducer mentioned above, it has been found that the frequency of the drive pulse and the drive speed are not in a proportional relationship, when the frequency of the drive pulse exceeds a certain range, the drive speed is decreased and there is a limit in increasing the drive speed even when the frequency of the drive pulse is increased.